Browsing by Author "Sivakholundu, K. M."

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A description of tidal propagation in Hooghly estuary using numerical and analytical solutions
(Ocean Engineering, 2018) Jena, B. K.; Sivakholundu, K. M.; Rajkumar, J.
A tidal propagation characteristic of Hooghly estuary is presented using numerical (ADCIRC) and analytical models (Friedrichs and Aubrey, 1994) along with observations. The analytical model is based on Friedrichs and Aubrey (1994) that simplifies the governing hydrodynamic equations greatly by retaining only those terms that are significant without losing the overall understanding of the propagation process. The analytical model is compared with corresponding 2-D depth averaged numerical (ADCIRC) model that retains all non-linear terms. The assumptions for simplification are found to be reasonable in the light of close agreement among analytical, numerical models and observations. A plan-form geometrical characteristic as well as hydrodynamic variable of the Hooghly has been compared with that of Delaware estuary for corroborating similar tidal propagation process. The Hooghly estuary has flood dominant asymmetric tidal propagation and a positive amplitude growth factor (μ). The observed tidal celerity (phase speed) on an average is slightly more than frictionless celerity. Using the conventions of Toffolon et al. (2006), Hooghly can be classified into ‘strongly convergent – strongly dissipative’ estuary. From the results it can be construed that the estuary is yet to stabilise and reach its equilibrium morphology. It can be close to its equilibrium as very little amplification (0.1 m) is noticed in the predominant semi-diurnal constituent M2 over 78 km (barely 7%) in the estuary. The parameters of width variation (γ) and the ratio between friction and inertia (χ) have been used to define the marginal condition for amplification. The relative position of Hooghly in terms of marginal condition is consistent with similar set of estuaries elsewhere that have been grouped using the above parameters.
A new archaeological find in the Gulf of Cambay, Gujarat
(Journal of the Geological Society of India, 2002) Kathiroli, S.; Badrinarayanan, S.; Venkata Rao, D.; Rajaguru, S.; Sivakholundu, K. M.; Sasisekaran, B.
Detailed underwater surveys carried out in the Gulf of Cambay, about 20 km west of Hazira, deploying side scan sonar and sub bottom profiler brought to light, the presence of a submerged palaeochannel traceable to a length of 9 km. Associated with this on either side are basement like features found in a grid pattern at water depths of 20-40 m. Sub-surface sampling carried out with dredge and grab sampler revealed stone artefacts, potsherds, hearth pieces, animal bones and human teeth embedded in fluvial sands and silts. In the upper part of the deposit, a carbonised wooden log was found and dated to around 9500 years BP by 14C method. Marine magnetic survey carried-out does not indicate the presence of any major metallic debrislobjects. This appears to be one of the early records of prehistoric human activity of early Holocene age in the marine environment of India.
A program to compute the area of an irregular polygon on a spheroidal surface
(Computers and Geosciences, 1998) Sivakholundu, K. M.; Prabaharan, N.
Application of parametric acoustics for shallow-water near-surface geophysical investigations
(IEEE, 2006-05) Vasudevan, Manoj; Sivakholundu, K. M.; Venkata Rao, D.; Kathiroli, S.
Shallow-water near-surface geophysical investigations were carried out, under two different scenarios - one to assess the status of a pipeline in the West coast and the other to assess the effect of water-injection dredging in the East coast of India. In both these investigations, Parametric Sediment Echo Sounder (SES-2000), a system developed by Innomar Technologie GmbH, which makes use of the parametric acoustical effect, was used. In the former case, profiles were taken across a pipeline at regular intervals to determine whether it was buried or exposed. The parametric system produces a 2D geo-acoustic section in which the pipe is indicated by a hyperbolic curve. The exposed height or buried depth of the pipeline at a crossing is then estimated. This investigation could, also, reveal the geomorphologic changes in the immediate vicinity of the pipeline. In the latter case, parametric acoustics was utilized to provide supplementary results for the assessment of water-injection dredging. Parametric acoustic data could expose the abrupt termination of certain near-seabed layer interfaces and sediment accumulations along steep slope, quite convincingly. SES-2000 proved to be handy to investigate the near-surface sub-seabed, especially in areas where conventional or popular methods find practical difficulties to be carried out.
Characterisation and performance of environment friendly natural antifoulants
(Indian Maritime University, Chennai, 2017) Joshi, Madhu.; Misra, S. C.; Mukherjee, Adithiya.; Sivakholundu, K. M.
In the middle of the 19th century antifouling paints were developed to prevent marine growth on ship hulls. Due to fouling, there is an increase in fuel consumption, reduction in vessel speed, increase in greenhouse emissions, acceleration of corrosion and propagation of invasive species. Today, ships are required to be drydocked every 5 years when the bottom hull is cleaned of fouling growth and painted with fresh coats of antifouling paint. Hull fouling takes place in marine environment in varying degrees. Density of marine organisms is higher in coastal water and since run-off from the land brings a wealth of food on which plankton exists, boats moored in harbours and estuaries are heavily fouled as paint depletion is low. There is an ongoing effort to improve the antifouling paint quality which can reduce fouling growth on hull surface and increase the gap in dry-docking schedules. But with this effort towards improving paint quality, it has been observed that paint components can be toxic causing ecological harm to ocean environment. Hence extensive research is being done in Natural Product Antifoulants (NPA). Natural product derivatives such as marine organisms like corals, sponges and seaweeds protect their body surfaces with several biochemical substances. Similarly, a wide array of terrestrial plants possess several natural compounds such as terpenes, acetylenes, polycyclic compounds, steroids, phenols, isothiocyanates, nitrogen containing compounds, glycerol derivatives, higher fatty acids and enzymes that are perhaps suitable as antifouling agents. Due to their availability and physio-chemical properties, Pongamia pinnata (Karanj) seed oil and Azadirachta indica (Neem) seed oil have been studied in the work for their potential use as antifouling agents. The bioassay studies against barnacle larvae reveal that Azadirachtin (Neem bioactive) has acute toxicity against barnacle larvae, percent motility inhibition being 64.78+3.95 at 0.5 µg.ml-1, 81.24+8.23 at 1.0 µg.ml-1and 100 at 5.0 µg.ml-1 in 24 hrs. Karanjin (Karanj bioactive) which also showed positive results against barnacle larvae at higher concentration, percent motility inhibition being 29.2+5.4 at 20 µg.ml-1 , 57.3+23.9 at 50 µg.ml-1and 85+25.9 at 100 µg.ml-1 in 4 hrs. The results of Neem toxicity also agrees with what was previously reported about Neem oil toxicity against L. Fortunei (Pereyra et.al., 2011) and Karanj oil has been used indigenously with Chandrus (a plant resin from members of the family Dipterocarpaceae) and lime in wooden boats to protect against termites Santhakumaran et.al., 1982). Marine exposure trials were conducted to find out the efficacy of Neem oil and Karanj oil in marine environment and these investigations on biocidal antifouling compositions were carried out at two sites at Visakhapatnam harbour. Environmental parameters such as temperature, salinity, pH and dissolved oxygen were monitored at the two stations. The seasonal pattern didn’t vary much during the field trials. The analyses of variances followed by post hoc tests of biofoulers recruitment both in terms of their numerical abundance and quantitative spread over the metal test plates from different points of view clearly demonstrated the usefulness of treatments in controlling biofouling formations at two sites at Visakhapatnam harbour despite spatial and temporal variations in the quality and quantity of biofouling on planted coupons. Analysis of variance conducted on the recruitment of Amphibalanus amphitrite amphitrite during various months as well as treatments at Visakhapatnam Fishing Harbour divulgedno significant difference in the abundance of this fouling barnacle species among various months (p=0.06), but projected very highly significant difference among various treatments given to the test plates (p = 4.78x10-8) signifying the effect of treatments over controls in curtailing the balanid recruitment. Thus, the overall assessment of performance of the bioactives of Karanj and Neem during the field exposure at the two sites in Visakhapatnam harbour in the backdrop of the performance of the Controls and Commercial antifoulant reveals that Neem bioactive is arginally better than Karanj bioactive and formulations incorporating still higher doses than the ones employed during the present investigation are required to achieve desired outcome of total prevention of biofouling on metal surfaces. Also, in order to significantly minimize fouling, antifouling (AF) painting schemes must also take into account the uneven hydrodynamic forces at the water-hull interface. If a correlation between wall shear stress at all locations on the vessels hull with rate of antifouling paint depletion is known, then the appropriate AF scheme could be applied. To obtain such a correlation the “Drum-Test” apparatus was devised, designed, manufactured and utilized. The results of paint film depletion of three self-polishing copolymer (SPC) antifouling paints versus time for various speeds of the drum indicated that Paint 3which was TBT free SPC antifouling paint with Cuprous oxide and organic biocides as active ingredients had maximum polishing rates while in Paint 1 which was TBT free SPC antifouling paint based on Copper acrylate, the polishing action was minimum. This implies that that Paint 1 could be coated for high speed high activity vessels such as ocean going vessels while Paint 3 would be an option for low speed low activity vessels such as harbour crafts, motor launch etc. This is expected to help in reducing the proportion of antifoulant in the proposed formulations paving way both for the development of eco-benign and cost-effective antifouling formulations. Key words: fouling, paint depletion, Natural product antifoulants, marine, terrestrial, bioactives, Commercial antifoulants, antifouling (AF) painting schemes, wall shear stress, Drum test apparatus, Selfpolishing Copolymer (SPC).
Design of sustainable shore protection solution using geosynthetic tubes
(GA 2016 - 6th Asian Regional Conference on Geosynthetics, 2016) Kiran, A.; Ravichandran, V.; Jebakumar, P.; Abhishek, T.; Sivakholundu, K. M.
Development of autonomous dredger for inland waterways and enclosed water bodies
(EADA(I) Silver Jubilee Seminar, 2018-03-15) Pavan Kumar, G. V. V.; Ramesh, U. S.; Sivakholundu, K. M.
The conceptual layout of the proposed autonomous dredger is presented. The potential for dredging in inland water bodies - reservoirs and inland waterways – in India is five times larger than the conventional dredging (ports and channels). Unlike arine dredgers, these small dredgers cannot be directly scaled up due to restrictions imposed by transportation, environmental conditions, draft and deployment. To overcome some of the difficulties, Indian Maritime University at Visakhapatnam campus IMU[V] is working on the development of an Autonomous Dredger (AD). The design philosophy revolves around modularity, ase of transport and autonomous operation. Modularity will ensure that the dredger can be dismantled for road transport and assembled at dredge site with minimal handling machinery. AD is being designed for calm water operations with four point mooring support and meant for clay and sand removal by water jet based dredging. The autonomous operation will ensure unattended dredging operation on 24x7 basis. The AD will have an in-built bathymetric survey system that will provide pre and post dredging quantification. While deployment the overall reservoir site will be divided into small ‘cell’ of convenient size (say 100 x 100m). After deployment, the AD will survey, dredge and verify the work done autonomously within the cell. Manual intervention for operational purpose will be kept to a minimum for shifting the AD from one cell to next.
Estuarine channel stability assessment through tidal asymmetry parameters
(Journal of Coastal Research, 2009-03) Sivakholundu, K. M.; Mani J. S.; Idichandy V. G.; Kathiroli S.
In an estuarine channel the tidal asymmetry, sediment transport, and morphology are interconnected. To maintain a stable channel, we need to take tidal asymmetry into account. A relationship connecting tidal asymmetry and sediment transport rate has been used to evaluate the relative merits of channel modification through numerical simulations. Two criteria have been identified for ensuring the channel stability: (a) maintaining ebb dominance and (b) minimizing the spatial gradient in the net sediment transport function ⟨q⟩. Using these criteria for a test case, we have evaluated Hooghly estuary (east coast, India), where heavy sedimentation is experienced and a permanent solution is needed. The approach provides better insight into the sedimentation pattern in a semidiurnal tidal process in a shallow estuary with braided channels. Among the factors affecting tidal asymmetry, the relative phase difference (β) between M2 and M4 current constituents has a major influence and is thus responsible for the sedimentation pattern. Through numerical study it was found that a combination of deepened, uniform channel with enhanced ebb flow led to a favorable β, indicating less deposition.
Evaluation of river regulatory measures in hughly estuary using tidal asymmetry characteristics
(IEEE, 2006) Sivakholundu, K. M.; Kathiroli S.; Mani J. S.; Idichandy V. G.
Tidal asymmetry has a profound effect on estuarine hydrodynamics and sedimentation pattern. The information of tidal asymmetry can be a useful tool to evaluate the flow pattern in shallow estuary and characterize the dominance of flood or ebb flow. The effects of features (like obstructions, depressions, etc.) and discharge variation in a theoretical channel section is simulated to quantify the parameters of tidal asymmetry. A set of proposed river regulatory measures in a shallow estuary (Hughly, India) was taken up for evaluation using tidal asymmetry parameters to check whether this may be used as additional tool. The indications provided (flood dominance and hence sediment importing regime) with asymmetry parameters do match with field conditions (based on bathymetry survey data). The asymmetry parameters may be put to use to evaluate the change in flood/ebb dominance in relative terms in a given section.
Long term morphodynamic evolution of Kakinada bay using upscaling methods
(Marine Engineers Review (India), 2020) Sharma, Garima.; Sivakholundu, K. M.; Patnaik, K. V. K. R. K.
Kakinada Bay has evolved over the last century dynamically by the action of wind, waves, tides and currents. Formation of Hope Island and development of Coringa Mangroves are attributed to the hydrodynamic 'forcings' and sediment dynamics. This study aims to predict the future morphological development of Kakinada Bay for next 100 years. The morphological model was built up in the DELFT 3D package. Model setting parameters were fixed after analysing their effect on the simulation results. For reducing the computational time and effort for simulating long term morphological development, upscaling methods such as morphological acceleration factor (MORFAC) and morphological tide were incorporated in the morphological model. Morphological tide was formed using tidal constituents - M2, O1 and K1. The MORFAC value for this study was chosen as 30 after undergoing the sensitivity test analysis using Brier Score Skill (BSS) Score. The model was run for 19 years for hindcasting and 100 years for forecasting. In order to establish confidence in the model, it was calibrated and validated using hindcast modelling. The hindcast simulation results were used to match the simulated shoreline with satellite observed shoreline from year 1988 to 2000, and 2006 to 2013 and the results were in good agreement. It was observed that the south-western part of the bay has accreted more rapidly while south-eastern part of the bay has undergone slight erosion. Thereafter long term morphological model was run for 100 years to predict the future evolution of bay. Results of these simulations show the capability of the long term morphological model to predict the spatial and temporal geo-morphological changes.
Long term port monitoring system (PMS)
(Indian Journal of Geo-Marine Sciences, 2014) Suseentharan, V.; Sivakholundu, K. M.; Jena, B.K.; Ravinder, M.; Balaji, R.
NIOT has developed and operated a Port Monitoring System (PMS) at Gujarat Pipavav Port Limited (GPPL) to measure tide and current on real time. PMS consists of a pressure based tide gauge and a Horizontal Acoustic Doppler Current Profiler (H-ADCP) installed at 5 m depth w.r.t Chart Datum (CD). Tide, current speed and direction are measured and transmitted to NIOT server in real time and data is presented through web application after quality check (QC). The success and high utility of the data at GPPL has resulted in requests for similar installations in other ports (Mundra, Dahej, Hazira, Vizhinjam, Dhamra and IGCAR) which enabled NIOT to expand the PMS network. The system can be used with different communication links like GPRS, UHF and INSAT. Using GPRS link, the sensors can be configured remotely to change the sampling regime and communication interval. Being a modular design, the PMS has an option for integrating more sensors for met-ocean and water quality parameters depending on site or study specific requirement. The paper discusses the basic architecture, options that can be built and the experience gained during development, installation and operation in various site conditions.
Managing a blackout : the consequences of an oil spill at sea /
(Taylor & Francis, 2022-09-08) Shankar, Malini S.; Sivakholundu, K. M.
The Ennore Oil Spill of 2017 triggered by a collision between two oil cargo vessels resulted in an environmental incident. This study is an attempt to cull the details from public domain and analyse the efficacy of the Government system to cope up with response. The information on events leading to the mishap indicates the suboptimal working conditions of seafarers prevailing on-board. The response activity drew negative publicity as the official communications were inconsistent. Besides declaring an under estimated quantum of oil spill, the perceived delay and inadequate resources seems to have aggravated the public sentiment. The episode of coastal spill clean-up came to close in two weeks with contributions from 30+ agencies of Government and industry along with 2000+ volunteers. The shoreline environment and fisheries activities returned to normalcy in three months’ time. Compensation to affected public was settled in a years’ time. However there is little information or unbiased evaluation of the episode available. An evaluation of such incidents will aid in addressing issues in future.
Quantification of changes in seabed topography with special reference to Hansthal Creek, Gulf of Kachchh, India.
(Journal of costal research, 1993-01) Pattanshetti, S.S.; Chauhan, Onkar.; Sivakholundu, K. M.
Variations in the bathymetry in macrotidal Hansthal Creek between 1984 and 1950 along 14 closely spaced lines, are used to quantify the volumetric changes in seabed topography in terms of erosion/accretion. Two surfaces from the bathymetric data of 1984 and 1950 have been modelled. The profile wise comparison along the transects indicates a dynamic deformation due to distinct alteration in the shoreline and a shift in the channel course. The shoreline has retreated 650 and 450 m on the northern and southern banks respectively. The studies suggest scouring of horizontally deposited fine sediments (clays deposited in an antecedent depositional phase) in the Hansthal Creek due to existing dynamic equilibrium among (a) influence of physiography in amplifying the tidal range, (b) increased efflux due to contribution through inter-creek water movements, and (c) high magnitude currents. Magnitude of erosion in the creeks, particularly on the flanks, is much more than in the axial channel. The degree of the erosion reduces from the Hansthal Creek mouth to inland (area in the close vicinity of Little Gulf of Kachchh). During the last 34 years about 71.5 x 10 super(6) m super(3) from this creek during the course of the present study. Offshoreward movement of scoured sediments and their redeposition in the outer gulf as a fill in the paleo-channel is observed.
Seasonal and interannual changes of significant wave height in shelf seas around India during 1998–2012 based on wave hindcast
(Ocean Engineering, 2018) Sanil Kumar, V.; Dubhashi, K. K.; Amrutha, M. M.; Joseph, Jossia; Jena, B.K.; Sivakholundu, K. M.
Present study examines the interannual changes of significant wave height (Hs) in shelf seas around Indian mainland based on the 15-year (1998–2012) wave hindcast data obtained from numerical model. Validation of the hindcast data with buoy-measured data shows that hindcast Hs is reasonably in good agreement with the observation (Pearson correlation coefficient values of 0.92–0.97). Annual average Hs varied from 0.9 to 1.4 m and the wave heights are higher (∼20%) in western shelf seas compared to eastern shelf seas. The analysis reveals seasonal fluctuations of wave climate, with a strong influence of Asian summer monsoon in the western shelf seas compared to the eastern shelf seas of India. Maximum Hs varied from 3.65 to 7.36 m and these maximum values were during the tropical cyclones. During 1998 to 2012, a statistically significant positive trend of 0.8–1.4 cm yr−1 in annual mean Hs is observed and the increasing trend is higher (∼0.7–2.5 cm yr−1) during the Asian summer monsoon period (June–September). The average trend of annual mean wind speed is also positive and is higher (∼1.67 cm s−1 yr−1) for the western shelf seas than that for eastern shelf seas (∼0.93 cm s−1 yr−1).
Seasonal variation in nearshore wave characteristics offCuddalore, Southeast coast of Tamil Nadu, India
(Current Science, 2017-05) Jena, B. K.; Patra, Sisir K.; Joseph, K. Jossica; Sivakholundu, K. M.
Wave data collected using wave rider buoy between January 2010 and January 2011 off Cuddalore coast, Tamil Nadu, India, have been analysed season-wise in this study. Wave steepness method was used for the separation of sea and swell wave parameters. Also parameters such as significant wave height of total wave, sea and swell (Hs , Hsw and Hss), zero crossing periods (Tz, Tsw and Tss) and mean wave directions (,sw and ss) have been studied. The study shows a distinct shift in sea wave direction of about 90 between June and October as well as November and February. Throughout the year, the predominant swell direction remained around 135. The contribution in total Hs by Hsw was 76% and the remaining 24% by Hss in the yearly cycle. The sea wave height was dominant by more than 90% during November to May. Regression analysis showed good positive Pearson’s correlation of 0.94 between Hs and Hsw; however, it was 0.65 between Hs and Hss. The maximum and significant wave heights of 5.7 and 2.7 m were recorded during cyclone Jal on 7 November 2010.
Short term morphological evolution of sandy beach and possible mitigation: A case study off Kadalur Periyakuppam
(Indian Journal of Geo-Marine Sciences, 2014-07) Sivakholundu, K. M.; Vijaya, R.; Kiran, A. S.; Abhishek, T.
Stability analysis and design of offshore submerged breakwater constructed using sand filled geosynthetic tubes
(Procedia Engineering, 2015) Kiran, A. S.; Ravichandran, V.; Sivakholundu, K. M.
Kadalur Periyakuppam (KPK) is a fishing village located 70 km south of Chennai in Tamil Nadu. The coastline of KPK was subjected to severe erosion due to high energy waves during Thane (2011), Nilam (2012) and Madi (2013) cyclones. The Tamil Nadu Fisheries department facilities located near the coast is subjected to damage as the coastline has receded by 45 m in the last few years following the severe erosion caused by cyclones. Since most of the erosion occurred after the storm waves hit the shoreline, sustainable option for shoreline protection would be to shift wave breaking to deeper depths. Based on numerical model studies and assessment of shoreline behaviour over two years, it is proposed to construct a submerged segmented breakwater. The submerged breakwater is proposed to be constructed at 4 m water depth up to a height of 3.5 m using sand filled geosynthetic tubes. Geosynthetic tubes shall be placed in a stacked manner with 2 tubes of 1.5 m high each at the bottom and a tube of 2.5 m height at the top accounting for height loss due to settlement. Design and stability checks are carried out by using available literature as no standard methods or design codes are available for design or stability checks for the geosynthetic tubes. The breakwater structure is checked for stability against sliding, overturning and bearing capacity. The geosynthetic tube material specifications such as tensile strength, ultra violet ray resistance, apparent opening size and fabric material are calculated using suitable design methods. The scouring, in front and behind the breakwater structure under prevailing wave conditions, is estimated for designing scour protection.
Surface current and wave measurement during cyclone Phailin by high frequency radars along the Indian coast
(Current Science, 2015-02) John, Manu; Jena, B. K.; Sivakholundu, K. M.
Cyclone Phailin originated in the east central Bay of Bengal (BoB) and crossed into the Indian mainland after traversing through the BoB. High frequency radar (HFR) operated by the National Institute of Ocean Technology could track the surface currents and high wave activity within its measuring limits. The radar data provide valuable information on the surface dynamics during the cyclone period. The HFR observations compare well with those of wave rider buoy. This opens up opportunities for observing the wave conditions during the cyclonic period over longer distances from the shore. This method is relatively more robust as HFR is less likely to be disrupted due to the passage of cyclones, unlike moored systems.
The long - term morphological development of kakinada bay
(Indian Maritime University, Chennai, 2022) Sharma, Garima.; Sivakholundu, K. M.
The evolution of Kakinada Bay with Coringa Mangroves at its southern shore and Kakinada Spit and Hope Island at its eastern side has occurred over the past century. This morphological development of the bay is attributed to the biophysical interactions, hydrodynamic forcing like waves, winds, tides, currents and sediment dynamics occurring inside the bay. The processes governing the short-term (decadal) and long-term (century) morphology of the bay need to be studied to develop sustainable coastal management plan for the intermediate time-scale. This study is an effort to extend the use of process based models to longer time scales to provide better understanding of the morphological development by the action of various physical processes governing alone and in combination. This study answers the question if these long-term morphological modeling can produce the reliable results by creating nexus of two techniques „Remote Sensing and Numerical Modeling‟. The numerical modeling hindcast results are validated using remote sensing images. This study quantifies the rate of change of the shoreline of the bay using remote sensing images in the Digital Shoreline Analysis System (DSAS). The trend of erosion and accretion occurring inside the bay was obtained using indices End Point Rate (EPR), Net Shoreline Movement (NSM) and Linear Regression Rate (LRR). The rate and trend of sedimentation and erosion obtained with the satellite imageries are further used to statistically compare the transect–wise hindcast and forecast results. Thus this study demonstrates the model‟s ability to reproduce the long-term morphodynamic development of the bay. This study attempts to investigate the action of physical processes on the morphological changes of the bay over a period of 100 years. For long term morphological modeling various approaches are followed like Input Reduction, Model Reduction and Acceleration techniques. Input reduction simulates the long term morphological modeling using schematized input data like morphological tide, schematized wave which are representative sets of the entire data. Model Reduction follows the approach of giving only the most important processes in the model input. Acceleration technique approach uses the morphological acceleration factor which accelerates the morphological development by the assigned factor. Available variants of the morphological predictions have been considered for the study. The study attempts to answer the hypothesis made to choose the appropriate approach between the two statements issued by Lesser (2009) and Roelvink (1999). The approach for adopting model reduction following the correct use of acceleration techniques as stated by Lesser (2009): “In order to use a morphological acceleration technique in a coastal situation it is essential to identify which coastal processes play a significant role in (residual) sediment transport patterns over the space and time scales of interest”. The second approach following the statement given by Roelvink (1999) and quoted by Dastgheib A. (2012) as: “If you put enough of the essential physics into the model, the most important features of the morphological behavior will come out, even at the longer time scales”. The exercise was varied with different environmental forcing with three scenarios: a) Tide only following Model Reduction, b) Tide and Wave Combined, c) Tide and Wave combined action with decadal MSL changes. The planimetric and decadal volumetric changes, shoreline changes have been compared for all the three scenarios. The outcome of the morphodynamic modeling from the different sets of physical processes will help to isolate the role of each physical process that are making difference in the overall morphological changes of the bay. It aims to isolate the effect of waves by comparing two simulations one with only tide and other with both wave and tidal forcing. The study with obtained forecast results will identify the areas under erosion and accretion and quantify the rate of shoreline changes. These results can help further in taking steps for coastal management. Thus this study gives an exemplary integration of the available techniques that can be helpful for coastal development modeling.
Use of swath data in realtime navigation by pattern recognition
(Marine Geodesy, 1989) Prabaharan, N.; Sivakholundu, K. M.
A new method is proposed with the aim of reducing dead reckoning error (DRE) during multibeam echosounding survey in deep ocean. Bathymetric data is used in this method to estimate DRE in position fixing. This method can be activated at any desired interval to check the DRE accumulation in addition to available external navigation systems. A pattern recognition algorithm is developed to quantify the shift in position of a selected bathymetric feature that has been observed already once. This difference is used to correct the position fixing and navigation data